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36 B clutch want snap into place

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Russell S.

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PostPosted: Tue Aug 14, 2007 6:01 pm    Post subject: 36 B clutch want snap into place Reply to specific post Reply with quote

I just reassembled the clutch on my unstyled John Deere b and I can't get the clutch to engage with a snap. What causes that distinct snap anyway? I do have alot of wear in the linkage and plan to get that built up and repaired. Wiil somebody help me understand how the clutch works on this old tractor?
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Chris in MD

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PostPosted: Tue Aug 14, 2007 6:29 pm    Post subject: Re: 36 B clutch want snap into place Reply to specific post Reply with quote

Well, if you have a parts catalog, you can understand it pretty darned good. I hope you have the service manual too.

The problem with your clutch is more than likely in the dogs and toggles that draw the 3 clutch pins in to tighten against the linings.

When you push in the clutch lever, a fork and yoke draws an operating sleeve towards the engine, thus drawing the toggles in further and further so that the threshold for snapping is reached. The reason that A clutch does not snap is because the toggles are severely worn, rendering the threshold for snap rather "floppy".

Have you tried torquing the adjusting bolts down 15 ft/lbs with the clutch engaged? IF that didn't work, then your toggles and dogs are worn. They are still available at Deere.

I have also welded up and turned down the yoke shaft, installed new pins in the levers, bored and bushed the pulley brake to the shaft, and a new clutch pin. When all the slack is gone, look froward to a nice snapping clutch.
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Joined: 21 Nov 2005
Posts: 264

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PostPosted: Tue Aug 14, 2007 8:26 pm    Post subject: Re: 36 B clutch want snap into place Reply to specific post Reply with quote

Got the same exact problem with my 36 B. I will pick up the new dogs and toggles from Deere tomorrow. Not cheap. It took me awhile to understand how they work, you need to study the manuals and there are also some good articles in Green and Two Cylinder mags.
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P Browning
Long Time User

Joined: 25 Jul 2005
Posts: 1466
Location: South Central Texas

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PostPosted: Wed Aug 15, 2007 3:03 am    Post subject: Re: 36 B clutch want snap into place Reply to specific post Reply with quote

Russell & CalJim -- This is one area where working with an early A or B is helped a bunch by use of the Parts Catalog for a later model of the tractor. Early parts catalogs do not show what many call an Illustrated Parts Breakdown that show how the parts fit to make the assembly. The clutch just didn't change that much from 36 or 37 to 1939. And so for the "B" tractor, a PC330 book would be super helpful.

Just a note on the clutch dogs, clutch dog pins and toggles: Do not be shy about putting plenty bearing grease on these parts. Now, many B144R toggles are needlessly replaced in hopes of getting a "new clutch". You can measure the ones you have for wear and wear patterns and decide. When new, they are 1.6875 inches long and their ball is 0.625 inches in diameter. The ball should be round and what wear is seem should be even. Because of the nature of clutch adjsutment, to find a bit of length loss isn't a main reason for clutch failure.

Russell -- The John Deere working principle is like that of any other in that drive is coupled from the crankshaft out toward the transmission by means of bring friction surfaces together under pressure. The major moving part is the operating sleeve which is moved when you go forward on the clutch operating lever. While you are moving the sleeve, you are prying against the adjusting disk or plate, and the plate is restrained by three operating bolts that connect it to the clutch dogs. It is at the operating bolts that you intervene to adjust the clutch. As the operating sleeve is moved to pressure the surfaces together, the clutch dogs come under pressure of the toggles (or dogbones). The dogbones bear on the toggle inward toward the shaft and (if operating bolts are set right) pass over dead center as the sleeve is moved into its "engaged" position. Passing over "dead cener" is what we call the snap.

Now, for most of us, the keys to successful clutch engagement includes getting the operating bolts set fairly close to where they should be, and also -- ensuring the belt pulley brake isn't fighting against you! See your operator's book for belt pulley brake adjustment.

Getting the operating bolts set right is a bit of art. For one thing, you must have thoroughly cleaned the threads on both nuts & bolts, and even a thread chase as well. They should be FREE to turn! Now -- when making the orignal setting I do two things. First I ensure the belt pulley brake adjustment is loose enough to where it is not a factor in restricting the clutch. Now for the good part -- with the clutch operating fork assembly in place & pulley brake out of the way, I move the clutch lever fully forward so the operating sleeve is in "engaged" position. Then with a wrench socket in hand (no handle), I hand turn each of the operating bolt nuts until snug. In this step is where FREE movement of the nut is so important so as to have EQUAL TENSION on all three. Try the clutch -- in & out looking for that snap. From this point forward, advance (in unison) each nut one constellation at a time to maintain tension equality until snap and release is achieved with between 40 and 80 pounds pressure applied at the end of the clutch handle. Be blessed! (PatB)
Restoration Site, JD-H
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Duane Larson
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Joined: 16 Apr 2003
Posts: 2448

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PostPosted: Wed Aug 15, 2007 4:47 am    Post subject: Re: 36 B clutch want snap into place Reply to specific post Reply with quote

As noted by others, I would surely check the dogs and toggles. However, the clutch drive pin that connects the operating sleeve to the main unit often becomes loose or worn. This allows the operating sleeve to rotate relative to the pulley unit, so the toggles don't stand straight during clutch engagement. When this happens the "snap" disappears. Try rotating the operating sleeve relative to the pulley. If there is movement the pin is loose or worn and needs to be inspected. There are three bosses on the operating sleeve, one of which is drilled to accomodate the drive pin. If the hole is worn, carefully drill a hole in another boss.
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Mike M
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Joined: 31 Mar 1998
Posts: 26249

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PostPosted: Wed Aug 15, 2007 5:03 am    Post subject: Re: 36 B clutch want snap into place Reply to specific post Reply with quote

Maybe I have been lucky ? I have rebuild several clutches over the years and I don't think I ever had to replace the toggles either. I had to swap out more than a few dogs because someone cropped off their ears.
Usually a good cleaning and lubing,tighten up the operating sleeve pin if really bad, put it all in right and use a torque wrench to tighten the 3 nuts evenly and it's good to go.
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